Generally, when a product such as an electronic product is packaged in a box, a buffer material such as Styrofoam has been frequently used to prevent the product from being broken or damaged by an external impact or an internal vibration.
However, such a buffer material has a great volume, which deteriorates the effective spatial utilization and increases costs during a distribution process, for example when being stored, piled up or carried. In addition, the buffer material is not recycled but wasted as it is after usage, which causes environmental pollution. As mentioned above, the buffer material has many problems.
Therefore, a buffer packing material having air cells formed therein by fusing a plurality of plastic films or sheets and filled with air to expand is used instead of Styrofoam.
In this buffer material, a pair of inner sheets having a plurality of air guiding paths are interposed between a pair of outer sheets by using a releasing band, and the pair of outer sheets and the pair of inner sheets are fused with each other to form a plurality of air cells, each of which has one air guiding path. Here, air is injected into an air injection path, which is formed by fusion and communicates with the plurality of air guiding paths, so that the plurality of air cells expands, thereby allowing the buffer material to be used.
In more detail, the overlapping upper and lower, outer and inner sheets are fused at regular intervals in a length direction to form a vertical fusion portion. Subsequently, the rear end of the upper and lower outer sheets is fused in a transverse direction to form a rear end transverse fusion portion, and the front ends of the upper and lower outer sheets and the upper and lower inner sheets are integrally fused to form a front end transverse fusion portion. At this time, a releasing band is formed in a transverse direction between the upper inner sheet and the lower inner sheet at the front end transverse fusion portion which is in contact with the end of the longitudinal fusion portion, so that a region having the releasing band formed is configured not to be fused. In this way, the air injected through the air injection path is injected into the air cells formed by the upper and lower outer sheets at regular intervals through the air guiding paths formed between the upper and lower inner sheets in the non-fused region as a passage.
With this configuration, if air is injected through the air injection path, the air cells are filled with air via the air guiding paths. In addition, if each air cell is sufficiently filled with air, the upper inner sheet and the lower inner sheet become into close contact with each other due to the pressure of the air filled in the air cell to close the air guiding path, so that the air in the air cells are not discharged to the outside.
However, the conventional buffer packing material as described above has no exit for the injected air when air is injected into the plurality of air cells through the air injection path at the same time. For this reason, if the internal pressure of the air injection path excessively increases, the air may be excessively injected into a certain air cell. In this case, the internal pressure of the corresponding air cell increases so that the outer sheet of the air cell is stretched and deformed. Therefore, there are problems in that it is difficult to put the product into a box of a certain shape, or the outer sheet or the fusion portion may be fractured to loss its buffer function.